Apparatus for heat-treating internal surfaces of metal articles



July 9, 1946. A. E. SHORTER I I 0 APPARATUS on HEAT TREATING INTERNAL SURFACES OF METAL ARTICLES Filed May 28, 1942 INVENTOR ALBERT E. SHORTER ATTORNEY Patented July 9, 1 946" c APPARATUS 'FoRf' HEAT-inguina INTER- METQL'ABIICLES Albert EdwardgSh orter, Sheifield,; England, as-

signor to TheLinde Air Produets company, New- .l l -lase m f #91 3 2 f I Application May 28, l 12-, SerialNo.444,804

' v-.InGreat.Britain June 4, 1941 *1 s Thi invention relates treatment of internal'metal surfaces and e5 9? cially to apparatus for the surface hardening of j such surfaces by theapplication .of high temper ature heat followed by quenching.

It i an object of this invention to'provide apparatus by which internal metal surfaces of .rel

atively small diameter, such as internal bearings,

may be uniformly treated; to provide such appa ratus by which all portions of. the internal sur face may be heated simultaneously, and. a heat-; ing unit adequately cooled; to provide apparatus. for treating internal metal surfaces by which, high temperature heating flames are directed;

against such a surface and an auxiliary combus tion-supporting medium is supplied to such. flames; to provide such apparatus which includes, a heat treatingdevice which is accurately 'loc at ed and guided during theheat treating-operation; to provide for a relative rotational moves ment between the heat treating devi'ce; andthe: work during such treatment, "and to produce more uniform heating and quenching. Other object 'and the novel features of this invention'will: become apparent from the following description and accompanying drawing in which:

Fig. 1 i a sectional elevation of the preferred.

form of heat treating device.

Fig. 2 is a transverse section taken along the" v .0:; Fig. 3 is a sectional elevation, illustrating a line 2-2 of Fig. 1.

modified form of heat treating'device, in operative position with respect to a surfaceto heat treated.

The heat treating device D comprise s, injcom f bination, a burner head l0 adaptedto be located in juxtaposition with respecti to the surface.

and having longitudinal gas passages therein with'radial as outlet H by which-hightemperature heating flames may be applied to the sur face, so as to heat the whole of the surface simultaneously; a quenching unitfl2,'co-axialwith the burner head and having. radial fluid ldis charge outlets l3; and a conduit M for the sup- 7 ply of fluid to the'quenching unit, the conduit extending through the burner head and acting as a thermal conductor to transferheat from ,the

burner head to the fluid passing to the. quenching unit,

Referring to Figs. 1 and 2, for details of the treating device D, the burner head H3 is secured, as by welding or brazing, to a ga distributing chamber 2| having an inlet 22 adapted to be connected to a pipe 23 supplying gaseous fuel; such as an oxy-acetylene mixture. Extending to pparatus for the hea f4 cia ai's'ficl.152F2 4) inwardly into the burner head. Hi from the end surfaceremote from the quenching unit- [2; and communicating with the distributing chamber 2|, are a .-plurality of :longitudinal gas passages 24-,symmetrically disposed with respect to the central v longitudinal; axis. -.From each passage 24.; there extends a eriesof the radial gas outlets I whichrare preferably arranged with the outlets-of onerowstaggered with respect to those of an adjacent row. The rows of gas outlets H preferably cover in the longitudinal direction a distance slightly less than the length of the bore to be treated, so that the terminal jets at each end do not impinge on-the edge of the bore but a short distance from the edge, thereby preventingoverheating. ofthe edge which is heated'substantially .solelylbywconduction. To reduce the tendency to backfire, each longitudinal gas passage 2-4 preferablytapers inwardlyfrom the open endas shown-in Fig. 2. The burner head H3 is preferablytmade of highly heat conductive metal such as copper in'iorder that heat may readily be transmitted to the cold fluid which is passed through the conduit [4.

In,view of the confined space within which the heat'treating device is primarily designed to operate, the-condition for combustion may not be ideal and inorder to facilitate combustion, mean may be provided for leading an auxiliary combustion-supporting medium to the combustion zone. This means may consist of longitudinally extending passages substantially entirely within the burner head, along which air as the auxiliary combustion-supporting medium may pass. by induction to the combustion zone. As

shown-in Fig; 2,'a' plurality of separate channels 26 may be provided in the burner head'terminating in;outlets or orifices;Zl'interspersed among the gas outlets, these separate channels 26 bemg supplied with air or other oxidizin gas. For

"this purpose, a pipe 28,'adaptedto be connected to an: auxiliary supply of combustion supporting gas such as air, extend through the chamber it fromthe upper end thereof and divides into two- ,tubes 2,91which lead to' channels 26 each having a series of radial discharge outlets 21.

The. quenching unit l2 comprises a chamber 30' closed at the end'remote from theburner head H) by aremovable plug 3| which permits ready access to the chamber 30 for cleaning purposes. A quenching medium, such as water, i supplied to chamber 30 from conduit I4, supplied by a tube or pipe 32 which extends through chamber 2! to the upper end of conduit M. In the wall of 55 the chamber 30 are formed the radial outlets l3 for discharging the quenching medium. These outlets are preferably arranged in rows which extend over a distance at least equal to the'length of the bore to be treated so as to insure thorough quenching of the whole of the heated surface.

In operation, the inlet pipe 23 is connected to a supply fuel of gas or suitable combustible mixture, the pipe 32 to a supply of cold fluid, and the pipe 28 to a source of compressed air or other combustion-supporting gas. The heating jets issuing from the burner orifices I l are lighted and the heat treating device thereupon inserted in the bore to be treated, the whole of the bore being heated simultaneously. After a predetermined time interval, suflicient for the surface of the bore to be raised above its critical temperature, the heat treating device is moved longitudinally so as to withdraw the burner head Hi from its operative position and simultaneously to move the quenching unit 12 into the bore to quench the heated surface.

During the whole operation, the cooling fluid supplied to conduit 14 passes through the heat treating device and when the burner head Hl'is in operative position, the spraying of the fluid through the quenching orifices I3 serves solely to cool the fluid which has become heated during its passage through the burner head and which may be collected and re-used. When the quenching unit I2 is in operative position in the bore, the burner jets are preferably extinguished so that the cooling fluid reaches the quenching unit 12 very nearly at the supply temperature and therefore serves as a more efllcient quenching medium. I

When a succession of articles are to be treated, each having one or more bores to be hardened, it is of advantage to mount the articles in turn in a chuck or other rotatable supporting means and an apparatus for the heat treatment of a bearing surface will now be described by way of example with reference to Fig. 3.

A bearing member 35 having a central bore or bearing surface 36 to be hardened is mounted in a chuck, the jaws .31 only of which are shown. The chuck is rotatable about the central longitudinal axis of the bore and a heat treating device constructed as shown in Fig. 1 is mounted Within the bore. The details of the heat treating device bear the same reference numerals as in Fig. 1 and require no further description. The chuck is rotated so that the surface 36 may be uniformly heated by the heating flames emitted from the outlets H and when the surface has attained the critical temperature, the heat treating device is moved so as to withdraw the burner head ID from the bore and move :the quenching unit I2 into the position occupied previously by the burner head.

In order that the device may be speedily and accurately mounted within the bore suitable lo-' eating means may be provided. As shown in Fig. 3, the locating means may comprise a guide member 33 having a, central aperture for the reception of a guide pin '39 projecting from the plug 3|, which serves as a closure member for the quenching chamber 30. The central longitudinal axis of the guide pin 39 is coincident with that of the burner head I!) and quenching unit l2, and by mounting the guide member 38 so that the aperture therein is also located centrally with respect to the burner head l0 and quenching unit II, the heat treating device may be accurately mounted within the bore and guided during the movement from the heating to the quenching' ortions. T

The structural details of the heat treating device described above are given by way of example only and may obviously be modified without departing from the invention as definedin the appended claims. 7

What is claimed is:

l. A device for heat treating an internal surface of a hollow metal article, comprising a burner head adapted to be inserted within the article and having a plurality of longitudinally extending rows of transversely extending outlets for directing high temperature heating flames against said surface; and passages terminating in longitudinallyextending rows of transversely extending outlets between adjacent pairs of said outlet rows, for supplying an auxiliary combustion supporting gas to said heating flames.

2. A device for heat treating an internal surface of a metal article, comprising a burner head adapted to be inserted within the article and having a plurality of annularly spaced longitudinally extending combustible gas passages therein terminating in longitudinally extending rows of transversely extending outlets for directing high temperature heating flames against said surface; and longitudinally extending passages substantially entirely within the burner head between adjacentv pairs of said combustible gas passages and opening laterally between said rows of outlets for supplying an auxiliary combustion supporting gas to said heating flames.

3. A device for heat treating an internal surface of a metal article comprising a burner head adapted to be inserted within the article and having a plurality of symmetrically disposed longitudinally extending combustible gas passages therein terminating in transversely disposed outlets for directing high temperatureheating flames against said surface; a plurality of symmetrically disposed longitudinally extending passages substantially entirely within the burner head each located between an adjacent pair of combustible gas passages and opening between said rows of outlets for supplying an auxiliary combustion supporting gas to said heating flames; and a central longitudinal passage at least coextensive with said rows of combustible gas outlets for the passage of cooling fluid to cool said burner head.

4. A device for heat treating an internal surface of a metal article, comprising a burner head adapted to be inserted within the article and having a plurality of symmetrically arranged longitudinally extending rows of transversely extending outlets for directing high temperature heating flames against said surface so as to heat substantially the whole of said surface simultaneously; and longitudinally extending passages substantially entirely within theburner head between adjacent pairs of said rows on opposite sides of said burner for supplying an auxiliary combustion supporting gas to said heating flames.

ALBERT EDWARD SHORTER. 

